The ability to evaluate cardiac function in small animal models has progressed significantly within the last five years. No longer a novelty, mouse echocardiography is now widely utilized and accepted. The adaptation of increasingly sophisticated high resolution imaging systems developed originally for humans now enables imaging of both adult (about 30 grams in mass) and neonatal mice (about 1 gram in mass). In addition, experience in imaging the heart and great vessels of chick embryos (El0-15) is gaining rapidly. These techniques require the collaborative input of several individuals including a primary investigator, who has generated the animal model to be tested, and an experienced sonographer to obtain, record, and interpret the image data. In mouse echocardiography, M-mode and intracoronary probes are employed to assess chamber size, fractional wall shortening, and ejection fraction. With Doppler capability, one can also assess flow rates. Transesophageal imaging, furthermore, can also be employed to provide high resolution imaging of the great vessels. In the day 10 to 15 chick embryo, furthermore, assessments of cardiac output can also be made. These studies require dedicated probes, access to imaging systems, and dedicated off-line image analysis equipment. In addition, they require skilled and dedicated assistance of a sonographer with extensive echocardiographic experience for acquisition, analysis, and interpretation of the data. In this application, we request funds for the purchase of an Acuson Sequoia C256 echocardiography system for the analysis of cardiac function in small experimental animals. At least seven investigators at Weil-Cornell anticipate employing this apparatus to conduct a total of 1500 to 2200 ECHO studies per year. The project has the approval of the Weil-Cornell Research Animal Resource Center. In addition, the institution has committed to providing salary support for a technical assistant and service contract funds until such time as the instrument becomes self-supporting.